Redirect to login on 401 and return afterwards

The SPA now sends the user to a new /login page whenever an API call
answers 401, remembering the page they were on. The OIDC callback always
lands back on the configured post-login redirect, so the saved page is
restored client-side once a session exists.

- auth: save/restore the return path in sessionStorage; defer the
  navigation so the failing request can finish first
- api: centralize 401 handling (me() still treats 401 as logged out)
- login page + shared login card, extracted from the lobby
- guard async signal writes so an in-flight request cannot touch a page
  unmounted by the redirect

web/Cargo.toml

@@ -13,7 +13,7 @@ serde_json = "1"
 wasm-bindgen = "0.2"
 wasm-bindgen-futures = "0.4"
 futures = "0.3"
-web-sys = { version = "0.3", features = ["Window", "Location", "Clipboard", "Navigator", "console"] }
+web-sys = { version = "0.3", features = ["Window", "Location", "Clipboard", "Navigator", "console", "Storage"] }
 js-sys = "0.3"
 gloo-timers = "0.3"
 console_error_panic_hook = "0.1"

web/src/api.rs

@@ -1,13 +1,32 @@
 //! REST client for the tavolo backend. Same-origin requests carry the
 //! session cookie automatically.
+use crate::auth;
 use crate::model::*;
-use gloo_net::http::Request;
+use gloo_net::http::{Request, Response};
 
 fn server_error(status: u16) -> String {
     format!("server returned {status}")
 }
 
+/// Map a failed response to an error. A `401` additionally starts the
+/// login flow: the session is gone (or the caller was never logged in),
+/// and the user is returned to this page after logging in.
+fn check(resp: &Response) -> Result<(), String> {
+    if resp.status() == 401 {
+        auth::redirect_to_login();
+        return Err("login required".to_string());
+    }
+    if !resp.ok() {
+        return Err(server_error(resp.status()));
+    }
+    Ok(())
+}
+
 /// Fetch the current user; `None` when unauthenticated (401).
+///
+/// Deliberately bypasses [`check`]: an unauthenticated answer is how the
+/// app renders its logged-out state, so it must not trigger the login
+/// redirect.
 pub async fn me() -> Result<Option<User>, String> {
     let resp = Request::get("/api/me")
         .send()
@@ -28,9 +47,7 @@ pub async fn auth_providers() -> Result<Vec<AuthProvider>, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     let page: AuthProvidersPage = resp.json().await.map_err(|e| e.to_string())?;
     Ok(page.providers)
 }
@@ -41,9 +58,7 @@ pub async fn game_types() -> Result<Vec<GameTypeInfo>, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     let page: GameTypesPage = resp.json().await.map_err(|e| e.to_string())?;
     Ok(page.results)
 }
@@ -58,9 +73,7 @@ pub async fn create_game(game_type: &str, options: serde_json::Value) -> Result<
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     resp.json().await.map_err(|e| e.to_string())
 }
 
@@ -71,6 +84,10 @@ pub async fn join_game(code: &str) -> Result<GameView, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
+    if resp.status() == 401 {
+        auth::redirect_to_login();
+        return Err("login required".to_string());
+    }
     if !resp.ok() {
         let body: serde_json::Value = resp.json().await.unwrap_or_default();
         let message = body
@@ -94,9 +111,7 @@ pub async fn join_preview(code: &str) -> Result<Option<JoinPreview>, String> {
     if resp.status() == 404 {
         return Ok(None);
     }
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     resp.json().await.map(Some).map_err(|e| e.to_string())
 }
 
@@ -135,9 +150,7 @@ pub async fn my_games() -> Result<Vec<MyGame>, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     let page: MyGamesPage = resp.json().await.map_err(|e| e.to_string())?;
     Ok(page.results)
 }
@@ -148,9 +161,7 @@ pub async fn my_matches(cursor: Option<&str>) -> Result<MatchesPage, String> {
         None => "/api/me/matches?limit=10".to_string(),
     };
     let resp = Request::get(&url).send().await.map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     resp.json().await.map_err(|e| e.to_string())
 }
 
@@ -160,9 +171,7 @@ pub async fn my_ratings() -> Result<RatingsPage, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     resp.json().await.map_err(|e| e.to_string())
 }
 
@@ -173,8 +182,6 @@ pub async fn leaderboard(game_type: &str) -> Result<LeaderboardPage, String> {
         .send()
         .await
         .map_err(|e| e.to_string())?;
-    if !resp.ok() {
-        return Err(server_error(resp.status()));
-    }
+    check(&resp)?;
     resp.json().await.map_err(|e| e.to_string())
 }

web/src/auth.rs

@@ -0,0 +1,74 @@
+//! Client-side login redirect handling.
+//!
+//! The OIDC callback always returns the browser to the configured
+//! post-login redirect (usually `/`), and the backend's login flow has no
+//! per-request `next` support. So when the API answers `401`, the page the
+//! user is on is saved in `sessionStorage` and restored once a session
+//! exists again.
+use sycamore_router::navigate_replace;
+
+/// `sessionStorage` key holding the page to return to after login.
+const RETURN_TO_KEY: &str = "tavolo.login.return_to";
+
+fn session_storage() -> Option<web_sys::Storage> {
+    web_sys::window()?.session_storage().ok().flatten()
+}
+
+/// The current page (path plus query), the URL to come back to after
+/// login.
+pub fn current_path() -> String {
+    let Some(location) = web_sys::window().map(|w| w.location()) else {
+        return String::new();
+    };
+    format!(
+        "{}{}",
+        location.pathname().unwrap_or_default(),
+        location.search().unwrap_or_default()
+    )
+}
+
+/// Whether a path is a page worth returning to: not the login flow
+/// itself, and not an absolute/protocol-relative URL.
+fn is_restorable(path: &str) -> bool {
+    path.starts_with('/')
+        && !path.starts_with("//")
+        && !path.starts_with("/auth/")
+        && !path.starts_with("/api/")
+        && path != "/login"
+}
+
+/// Handle an expired session: remember the current page and go to the
+/// login page.
+///
+/// The navigation is deferred to a timer so the caller can finish handling
+/// the failed response (e.g. set an error) before its page is unmounted.
+pub fn redirect_to_login() {
+    let path = current_path();
+    if is_restorable(&path) {
+        if let Some(storage) = session_storage() {
+            let _ = storage.set_item(RETURN_TO_KEY, &path);
+        }
+    }
+    gloo_timers::callback::Timeout::new(0, move || {
+        // Several in-flight requests may fail at once; only the first
+        // takes us to the login page.
+        if current_path() != "/login" {
+            navigate_replace("/login");
+        }
+    })
+    .forget();
+}
+
+/// The page saved by [`redirect_to_login`], if any.
+pub fn saved_return_to() -> Option<String> {
+    let storage = session_storage()?;
+    let path = storage.get_item(RETURN_TO_KEY).ok().flatten()?;
+    is_restorable(&path).then_some(path)
+}
+
+/// Drop the saved page, e.g. after it has been restored.
+pub fn clear_return_to() {
+    if let Some(storage) = session_storage() {
+        let _ = storage.remove_item(RETURN_TO_KEY);
+    }
+}

web/src/components/login.rs

@@ -0,0 +1,70 @@
+//! Login card, shared by the lobby's logged-out state and the `/login`
+//! page.
+use sycamore::prelude::*;
+
+use crate::model::AuthProvider;
+
+/// Human-readable label for a provider name ("google" -> "Google").
+fn provider_label(name: &str) -> String {
+    let mut chars = name.chars();
+    match chars.next() {
+        Some(first) => first.to_uppercase().collect::<String>() + chars.as_str(),
+        None => String::new(),
+    }
+}
+
+/// Card offering one login button per configured provider.
+///
+/// `providers` is filled by the caller from `GET /api/auth/providers`;
+/// while it is empty (or the fetch failed) the card falls back to the
+/// generic `/auth/login` route, which redirects to the first configured
+/// provider.
+pub fn login_card(providers: Signal<Vec<AuthProvider>>) -> View {
+    view! {
+        div(class="status-card") {
+            div(class="card") {
+                div(class="card-body p-4") {
+                    h1(class="h3 mb-3") {
+                        span(class="text-warning") { "♠" }
+                        " tavolo"
+                    }
+                    p(class="text-secondary") { "Log in with your account to play." }
+                    // rel="external" opts out of the SPA router's click
+                    // interception: these must be full page navigations
+                    // to the backend's OIDC login endpoints.
+                    (move || {
+                        let providers = providers.get_clone();
+                        if providers.is_empty() {
+                            // Providers could not be fetched: the generic
+                            // route redirects to the first configured
+                            // provider.
+                            view! {
+                                a(
+                                    class="btn btn-warning btn-lg w-100",
+                                    href="/auth/login",
+                                    rel="external",
+                                ) {
+                                    "Log in"
+                                }
+                            }
+                        } else {
+                            view! {
+                                div(class="d-grid gap-2") {
+                                    (providers.iter().cloned().map(|p| view! {
+                                        a(
+                                            class="btn btn-warning btn-lg w-100",
+                                            href=p.login_url,
+                                            rel="external",
+                                        ) {
+                                            "Log in with " (provider_label(&p.name))
+                                        }
+                                    }).collect::<Vec<_>>())
+                                }
+                            }
+                        }
+                    })
+                }
+            }
+        }
+    }
+}

web/src/components/mod.rs

@@ -1,6 +1,7 @@
 pub mod briscola;
 pub mod card;
 pub mod copy;
+pub mod login;
 pub mod nav;
 pub mod summary;
 pub mod toast;

web/src/main.rs

@@ -1,22 +1,27 @@
 //! Application entry point.
 mod api;
+mod auth;
 mod components;
 mod model;
 mod pages;
 mod ws;
 
 use sycamore::prelude::*;
-use sycamore_router::{HistoryIntegration, Route, Router};
+use sycamore_router::{navigate, HistoryIntegration, Route, Router};
+use wasm_bindgen_futures::spawn_local;
 
 use pages::game::GamePage;
 use pages::history::HistoryPage;
 use pages::leaderboard::LeaderboardPage;
 use pages::lobby::LobbyPage;
+use pages::login::LoginPage;
 
 #[derive(Route, Clone)]
 enum AppRoutes {
     #[to("/")]
     Lobby,
+    #[to("/login")]
+    Login,
     #[to("/game/<id>")]
     Game { id: String },
     #[to("/history")]
@@ -27,6 +32,31 @@ enum AppRoutes {
     NotFound,
 }
 
+/// After the OIDC callback lands the SPA back on the configured
+/// post-login redirect, forward the user to the page they were on before
+/// being sent to the login page (see [`auth`]) — but only once a session
+/// exists, so a cancelled login never bounces into a stale page.
+fn restore_page_after_login() {
+    let Some(path) = auth::saved_return_to() else {
+        return;
+    };
+    spawn_local(async move {
+        match api::me().await {
+            Ok(Some(_)) => {
+                auth::clear_return_to();
+                if auth::current_path() != path {
+                    navigate(&path);
+                }
+            }
+            // Not logged in: keep the target for the next successful
+            // login (a reload of the login page must not lose it).
+            Ok(None) => {}
+            // The probe failed (offline?): keep the target, too.
+            Err(_) => {}
+        }
+    });
+}
+
 fn main() {
     console_error_panic_hook::set_once();
     sycamore::render(|| {
@@ -38,6 +68,7 @@ fn main() {
                         div(class="app") {
                             (match route.get_clone() {
                                 AppRoutes::Lobby => view! { LobbyPage() },
+                                AppRoutes::Login => view! { LoginPage() },
                                 AppRoutes::Game { id } => view! { GamePage(id=id) },
                                 AppRoutes::History => view! { HistoryPage() },
                                 AppRoutes::Leaderboard => view! { LeaderboardPage() },
@@ -60,4 +91,5 @@ fn main() {
             )
         }
     });
+    restore_page_after_login();
 }

web/src/pages/history.rs

@@ -105,18 +105,29 @@ pub fn HistoryPage() -> View {
         spawn_local(async move {
             match api::my_matches(next.as_deref()).await {
                 Ok(p) => {
+                    // The page can unmount (e.g. the login redirect) while
+                    // the request is in flight.
+                    if !page.is_alive() {
+                        return;
+                    }
                     cursor.set(p.next_cursor.clone());
                     rows.update(|acc| acc.extend(p.results.iter().cloned()));
                     page.set(Some(p));
                 }
-                Err(e) => error.set(Some(e)),
+                Err(e) => {
+                    if error.is_alive() {
+                        error.set(Some(e));
+                    }
+                }
             }
         });
     };
 
     spawn_local(async move {
         if let Ok(types) = api::game_types().await {
-            game_types.set(types);
+            if game_types.is_alive() {
+                game_types.set(types);
+            }
         }
     });
 
@@ -124,11 +135,18 @@ pub fn HistoryPage() -> View {
     spawn_local(async move {
         match api::my_matches(None).await {
             Ok(p) => {
+                if !page.is_alive() {
+                    return;
+                }
                 cursor.set(p.next_cursor.clone());
                 rows.set(p.results.clone());
                 page.set(Some(p));
             }
-            Err(e) => error.set(Some(e)),
+            Err(e) => {
+                if error.is_alive() {
+                    error.set(Some(e));
+                }
+            }
         }
     });
 

web/src/pages/lobby.rs

@@ -13,21 +13,13 @@ use sycamore_router::navigate;
 
 use crate::api;
 use crate::components::card::card_back;
+use crate::components::login::login_card;
 use crate::components::toast::toast;
 use crate::model::{
     fallback_game_types, is_individual_game, AuthProvider, GameTypeInfo, JoinPreview,
     MyGame, OptionField, OptionKind, PlayerRating, User,
 };
 
-/// Human-readable label for a provider name ("google" -> "Google").
-fn provider_label(name: &str) -> String {
-    let mut chars = name.chars();
-    match chars.next() {
-        Some(first) => first.to_uppercase().collect::<String>() + chars.as_str(),
-        None => String::new(),
-    }
-}
-
 fn json_to_string(value: &serde_json::Value) -> String {
     match value {
         serde_json::Value::String(s) => s.clone(),
@@ -386,18 +378,30 @@ pub fn LobbyPage() -> View {
                 if me.is_some() {
                     spawn_local(async move {
                         if let Ok(p) = api::my_ratings().await {
-                            ratings.set(p.results);
+                            if ratings.is_alive() {
+                                ratings.set(p.results);
+                            }
                         }
                         if let Ok(games) = api::my_games().await {
-                            my_games.set(games);
+                            if my_games.is_alive() {
+                                my_games.set(games);
+                            }
                         }
                     });
                 }
-                user.set(Some(me));
+                // The page may have been unmounted (e.g. by the login
+                // redirect triggered while this request was in flight).
+                if user.is_alive() {
+                    user.set(Some(me));
+                }
             }
             Err(e) => {
-                error.set(Some(e));
-                user.set(Some(None));
+                if error.is_alive() {
+                    error.set(Some(e));
+                }
+                if user.is_alive() {
+                    user.set(Some(None));
+                }
             }
         }
     });
@@ -405,6 +409,9 @@ pub fn LobbyPage() -> View {
     spawn_local(async move {
         match api::game_types().await {
             Ok(types) if !types.is_empty() => {
+                if !game_types.is_alive() {
+                    return;
+                }
                 selected_game.set(types[0].id.clone());
                 game_types.set(types);
             }
@@ -414,7 +421,9 @@ pub fn LobbyPage() -> View {
 
     spawn_local(async move {
         if let Ok(list) = api::auth_providers().await {
-            auth_providers.set(list);
+            if auth_providers.is_alive() {
+                auth_providers.set(list);
+            }
         }
     });
 
@@ -470,53 +479,7 @@ pub fn LobbyPage() -> View {
                         }
                     }
                 },
-                Some(None) => view! {
-                    div(class="status-card") {
-                        div(class="card") {
-                            div(class="card-body p-4") {
-                                h1(class="h3 mb-3") {
-                                    span(class="text-warning") { "♠" }
-                                    " tavolo"
-                                }
-                                p(class="text-secondary") { "Log in with your account to play." }
-                                // rel="external" opts out of the SPA router's click
-                                // interception: these must be full page navigations
-                                // to the backend's OIDC login endpoints.
-                                (move || {
-                                    let providers = auth_providers.get_clone();
-                                    if providers.is_empty() {
-                                        // Providers could not be fetched: the
-                                        // generic route redirects to the first
-                                        // configured provider.
-                                        view! {
-                                            a(
-                                                class="btn btn-warning btn-lg w-100",
-                                                href="/auth/login",
-                                                rel="external",
-                                            ) {
-                                                "Log in"
-                                            }
-                                        }
-                                    } else {
-                                        view! {
-                                            div(class="d-grid gap-2") {
-                                                (providers.iter().cloned().map(|p| view! {
-                                                    a(
-                                                        class="btn btn-warning btn-lg w-100",
-                                                        href=p.login_url,
-                                                        rel="external",
-                                                    ) {
-                                                        "Log in with " (provider_label(&p.name))
-                                                    }
-                                                }).collect::<Vec<_>>())
-                                            }
-                                        }
-                                    }
-                                })
-                            }
-                        }
-                    }
-                },
+                Some(None) => view! { (login_card(auth_providers)) },
                 Some(Some(_me)) => {
                     view! {
                         (crate::components::nav::app_nav("/", move || {

web/src/pages/login.rs

@@ -0,0 +1,41 @@
+//! Login page, shown after the API answered `401` (see [`crate::auth`]):
+//! the session expired, or the visitor tried to open a page that needs an
+//! account.
+//!
+//! The backend's OIDC callback lands the SPA back on the configured
+//! post-login redirect; [`crate::auth`] then returns the user to the page
+//! they were on before this one.
+use sycamore::prelude::*;
+use sycamore_router::navigate_replace;
+use wasm_bindgen_futures::spawn_local;
+
+use crate::api;
+use crate::auth;
+use crate::components::login::login_card;
+use crate::model::AuthProvider;
+
+#[component]
+pub fn LoginPage() -> View {
+    let providers = create_signal(Vec::<AuthProvider>::new());
+
+    spawn_local(async move {
+        // Already signed in: no business here — return to where the user
+        // was headed, or the lobby.
+        if matches!(api::me().await, Ok(Some(_))) {
+            let target = auth::saved_return_to().unwrap_or_else(|| "/".to_string());
+            auth::clear_return_to();
+            navigate_replace(&target);
+            return;
+        }
+        if let Ok(list) = api::auth_providers().await {
+            // The page can unmount while the fetch is in flight.
+            if providers.is_alive() {
+                providers.set(list);
+            }
+        }
+    });
+
+    view! {
+        (login_card(providers))
+    }
+}

web/src/pages/mod.rs

@@ -4,3 +4,4 @@ pub mod game;
 pub mod history;
 pub mod leaderboard;
 pub mod lobby;
+pub mod login;